In a method of electrical impedance tomography (EIT), a mediating fluid provides electrical contact between the electrodes of an EIT device and the skin of a body part to be examined. The height of the fluid is raised or lowered between impedance measurements, enabling tomographic images of the tissue under examination to be resolved mathematically for subsequent viewing. Tomographic planes are isolated by calculating differences between Cartesian models generated from impedance values measured at the plane of interest and at an adjacent plane.